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Egg cells are about the size of a grain of sand. They are formed inside of a female's ovaries before she is even born.
In the United States, there is a birth every 8 seconds, according to the U.S. Census Bureau's Population Clock.
Hippocrates noted that blood separates into four differently colored liquids when removed from the body and examined: a pure red liquid mixed with white liquid material with a yellow-colored froth at the top and a black substance that settles underneath; he named these the four humors (for blood, phlegm, yellow bile, and black bile).
Bacteria have been found alive in a lake buried one half mile under ice in Antarctica.
Signs of depression include feeling sad most of the time for 2 weeks or longer; loss of interest in things normally enjoyed; lack of energy; sleep and appetite disturbances; weight changes; feelings of hopelessness, helplessness, or worthlessness; an inability to make decisions; and thoughts of death and suicide.